PAF "Platelet Activating Factor" possesses the structure of a phospholipid and is a chemical transmitter which exists in living organisms. It has been clarified that PAF, as its in-vivo function, is closely involved in allergy, anaphylaxis and inflammation as well as platelet aggregation, and furthermore, PAF is known to exhibit potent hypotensive activity.
When PAF is given to animals, on the other hand, complication of these activities causes the animals to produce symptoms of shock, occasionally leading to death. The shock produced by PAF resembles symptoms of shock due to endotoxin, and PAF is suspected to be involved in the endotoxin shock.
With reference to the metastasis of cancer, it is thought that platelet aggregation is implicated in the stage of implantation of cancer cells, and lipid derivatives having the ether and carbomoyl bonds, because enzymes capable of breaking such bonds are deficient particularly in cancer cells, further tend to accumulate in cancer cells and exhibit the action to bring about change in the lipid metabolism within the cancer cell, eventually resulting in death of cancer cells.
The present inventors, after intensive search into lipid derivatives having the PAF inhibitory activity which are valuable as a preventive and therapeutic agent for a variety of circulatory disturbances and diseases and allergic disorders and also as an antineoplastic agent, succeeded in the production of lipid derivatives exhibiting excellent activities and have come to complete the present invention.